1. Field of the Invention
The present invention generally relates to textile treating machines and, more particularly, to heat exchangers for industrial or institutional fabric treating machines.
2. Description of the Related Art
In industrial or institutional fabric treating machines, and continuous batch laundry systems (tunnels), a large volume of liquid is required to treat the fabrics. Since such a large quantity of liquid is used, preliminary heating of the treating liquid prior to its introduction into the machine, which is conventional in smaller household machines, is neither economically nor operationally practical.
Therefore, in conventional fabric treating machines, treating liquid is introduced into the imperforate outer tub or shell and thereafter heated to the desired temperature. The process for heating the treating liquid bath, and for subsequently maintaining the bath at a desired temperature, has generally been accomplished by one of two known methods.
The first known method of heating uses a series of pipes to carry the treating liquid to an external heater where it is heated and thereafter returned to the fabric treating machine. The treating liquid is maintained at the required temperature for treating the fabrics by continuous recirculation and heating.
In heating methods of this type, an extra ten to twenty percent of treating liquid is required to maintain the bath volume and temperature within the desired operating range. However, due to the small amount of treating liquid heated at one time, there is a tendency for undesirable temperature spikes or gradients to develope within the treating liquid bath.
Heating methods of this type suffer from the further disadvantage that they are generally inefficient, losing a certain amount of the heat acquired from the external heater while returning to the fabric treating machine. Insulation is required to minimize conduction losses. Also, the continuous circulation of treating liquid requires auxiliary equipment such as pumps, hoses, valves and fittings, increasing the product cost and further decreasing efficiency.
The second known method of heating uses a heat exchanger attached to the inside of the fabric treating machine. Heat exchangers of this type generally include a series of conduits to carry a heat exchanging fluid through the fabric treating machine. The known heat exchangers used in this method of heating are permanently welded to the inside surface of the imperforate outer shell intermediate the outer tub and the perforate spin tub.
Welded-in-place heat exchangers are susceptible to cracking and corrosion which requires costly and time-consuming repair or replacement. Furthermore, during repair, maintenance, or cleaning, the spin tub must be removed to gain access to the heat exchanger, a very costly and labor intensive procedure which takes the machine out of service for an extended period of time. Thus, heat exchangers of this type suffer from the disadvantage that they are not easily accessible when maintenance is required and that the machine is inoperable during repair of the heat exchangers.
Therefore, there exists a need in the art for an efficient heat exchanger which is easily accessible to allow quick repair and replacement thereof.